Blood culture

Overview

A blood culture is a test that looks for bacteria or fungi in your blood. It helps doctors find serious infections like sepsis, which is a dangerous body-wide response to infection.

Blood culture is a common test in hospitals when a serious bloodstream infection is suspected.

It is used for people of any age who have signs of a severe infection, such as high fever, chills, rapid breathing, or confusion.

Symptoms

Common symptoms

• Fever or chills
• Rapid heart rate
• Rapid breathing
• Feeling very tired or weak
• Confusion or disorientation

Symptoms in children

• Irritability or fussiness
• Poor feeding or vomiting
• Fever or low body temperature
• Lethargy (hard to wake)

Symptoms in older adults

• Confusion or sudden change in mental state
• Weakness or difficulty moving
• Low blood pressure
• Loss of appetite

Causes

Main causes

• Bacteria entering the bloodstream from an infection in another part of the body, such as the lungs (pneumonia), urinary tract, skin, or abdomen.
• After surgery, an infected wound or device (like a catheter) can introduce germs into the blood.

Risk factors

• A weakened immune system (due to illness, chemotherapy, or long‑term medicines like steroids)
• Being very young or very old
• Recent surgery or invasive procedures
• Having an intravenous (IV) line, catheter, or other medical device in the body

When to see a doctor

See a doctor urgently if:

• If you have a fever and chills that get worse over a few hours
• If you feel very tired, confused, or have trouble breathing

Book a routine appointment if:

• If you have a mild fever that lasts more than 3 days without other symptoms

Diagnosis

A doctor or nurse will take a blood sample from a vein in your arm using a needle. You may need more than one sample taken at different times or from different sites.

Tests that may be done

• Blood culture (one or more samples)
• Complete blood count (CBC) to check for infection markers
• Blood chemistry tests to see how organs are working

What to expect at your appointment

The blood samples are sent to a laboratory where they are placed in special bottles that help bacteria grow. Results usually come back in 2 to 3 days. Your healthcare team will use the results to decide the best treatment.

Treatment

The main goal is to fight the infection and support your body while it recovers. Most people need to be treated in the hospital, especially if the infection is severe.

Self-care at home

• Get plenty of rest
• Drink enough fluids (water, clear broths) to stay hydrated
• Follow your doctor’s instructions exactly, including taking all prescribed medicines

Medical treatments

You will likely receive antibiotics given through a vein (intravenous). The specific type of antibiotic depends on the results of the blood culture. Sometimes two or more antibiotics are used together. You may also receive fluids, medicines to keep your blood pressure stable, and medicines to reduce fever.

When is surgery considered?

If there is a pocket of infection (abscess) somewhere in the body, or if an infected medical device needs to be removed, surgery may be necessary.

Living with this condition

After treatment, you may feel tired for several weeks. You will need follow‑up blood tests to make sure the infection is gone. Your doctor will tell you when you can return to normal activities.

Lifestyle tips

• Wash your hands often and keep any wounds clean to prevent new infections
• Avoid being around people who are sick if your immune system is weak
• Let your healthcare team know about any new symptoms right away

Diet and exercise

Eat a balanced diet with plenty of fruits, vegetables, and protein to help your body recover. Gentle activity like short walks can help, but rest is most important in the early days.

Mental health and emotional wellbeing

It is common to feel worried, anxious, or down after a serious infection. Talk to your doctor or a counselor about your feelings. You are not alone.

Prevention

Not all bloodstream infections can be prevented, but you can lower your risk by treating infections early, keeping good hygiene, and following your doctor’s advice about caring for any wounds or medical devices.

Vaccines

Vaccines against the flu, pneumonia, and other infections may help prevent some serious infections that can lead to a positive blood culture. Ask your healthcare provider which vaccines are right for you.

Complications

If left untreated

• Sepsis (a dangerous, body‑wide inflammatory response that can cause organ failure)
• Septic shock (very low blood pressure and organ damage)
• Death

Long-term outlook

With prompt and appropriate treatment, most people recover fully from a bloodstream infection. Doctors and nurses will monitor you closely to prevent complications and support your recovery. There is good reason for hope.

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